Field of the Invention
The invention concerns a process and an apparatus for the realization of said process to obtain the homogeneous transverse heating of long and thin, conducting products, passing continuously, in electromagnetic induction heating assemblies.
The invention particularly concerns an assembly in which heating is induced by a moving magnetic field, created by the rotation of a relatively constant magnetic field, with the work product in contact with a support drum having the same axis of rotation as the inductor assembly.
An apparatus of this type is known in the prior art wherein a rotating hollow support of a refractory material houses a rotor entrained by a motor, comprising several poles supplied with continuous current of alternating polarity between adjacent poles. The moving magnetic field is generated by rotation of the inductors entrained by a motor. A yoke is provided to insure the return of the flux around the loop formed by the product passing around the rotating support. An inlet and outlet roller are provided for the product. The rotating support and the work product are thus located in the space between the inductor rotor and the return yoke of the flux.
It should be noted that such an apparatus provides very efficient inductive heating and eliminates the need for installations to compensate for reactions due to the poor power factor of devices supplied with an alternating current.
If the transverse profile of the magnetic field is uniform over the entire width of the product to be heated, however, the surface power induced is constant over the width for a product of infinite width only. In the case of a product with a finite width, the closure of the induced currents generates a variation of the surface power induced, which is a function of the wave length of the sliding field (see the diagram of FIG. 1 of the drawings attached hereto of the magnetic induction B and the induced power P) and of the dimensions of the product.